1. Field of the Invention
This invention relates to a processing machine for the surface treatment of workpieces in which a push rod which can be reciprocated is connected to a processing tool, and is put in motion by a driven eccentric drive assembly; the imbalance of the eccentric drive is balanced by means of an eccentric mass balance assembly with the eccentric of the eccentric drive assembly and the countereccentric of the eccentric mass balance assembly being of equal size and being arranged in a torsion-resistant fashion and opposed by 180.degree. on a drive shaft.
2. Description of the Prior Art
A processing machine of this general type, designed as a saw, has been described in U.S. Pat. No. 1,648,008. The two eccentrics and their eccentric casings are coupled, on the one hand, directly with the saw blade and on the other hand, with the balancing element. Furthermore, the working range of the eccentric mass balance with reference to the drive shaft is in a direction other than that of the processing tool, so that this type of drive is not suited for manual devices for surface treatment.
A device for the mass balance of machines driven by a crank drive is described in German Patent DE-PS No. 25 34 626. This well known device provides two eccentrics mounted on bearings and placed into each other which control a complicated and expensive lever bar with a counterbalance weight that is not suitable for a device for surface treatment.